"Always fun to have bogey-free days, especially around this golf course," said Kuchar. "(I) just drove it well today, which is a big key around here. The greens are pretty tricky and pretty firm this year, so coming out of the rough, it's difficult to get a ball to stop close to the hole."

Sergio Garcia sits alone in second place after firing a 65 as part of the afternoon wave. The Spaniard hit eight fairways and 12 greens, while using just 25 putts.

Brandt Jobe shot 66 to take sole possession of third place, while rookie James Hahn, Charlie Beljan and David Lynn share fourth at 4-under 67.

Lee Westwood and Fred Couples highlight a large group which shot 68. They are a stroke ahead of world No. 3 Luke Donald and 2011 Masters champion Charl Schwartzel, who are both making their PGA Tour season debuts.

Defending champion Bill Haas, who defeated Phil Mickelson and Keegan Bradley in a playoff last year, carded a 70. Mickelson and Bradley both shot even-par.

"It was just a fraction off, because I hit the ball pretty solid yesterday (during the pro-am)," said Mickelson.. "I felt like I was on the right track, and when I came out this morning, it was a little bit off. I was hitting some pull hooks, I was hitting some block cuts, and so I put myself in some not great spots off the tee."

Adam Scott, the 2005 champion at this event, also shot even-par in his first round of the 2013 PGA Tour campaign.

Kuchar's 64 marked his best-ever score at Riviera.

He began the round in fine form, picking up three straight birdies to start. Teeing off at the par-5 first, Kuchar two-putted from 29 feet before tapping in from less than three feet on Nos. 2 and 3.

After picking up another birdie at the seventh, Kuchar opened his inward nine by nailing the green on the driveable par-4 10th and two-putting from 58 feet for another birdie.

Kuchar, who has two top-10 finishes in three previous starts this season, closed his sparkling round by making consecutive birdie putts from inside 10 feet at Nos. 16 and 17 to enter the clubhouse with the advantage.

"Things were going well (during practice) early in the week and still continuing, but I think the hot start was certainly a great way to get the round going," continued Kuchar.

NOTES: Kuchar has never had a top-10 finish in seven previous appearances at this event. His best result was a tie for 14th in 2008 ... Tiger Woods has played this tournament more times (11) without a victory than any other PGA Tour event. He has not played here since 2006 ... This week is the 87th staging of this tournament. Outside of the major championships, this is the fourth-oldest tournament on the PGA Tour. Only the BMW Championship, Canadian Open and Texas Open are older ... Last year, Haas holed an unlikely 43-foot birdie putt on the second playoff hole to defeat Mickelson and Bradley.